Glucocorticoid receptors in human peripheral blood mononuclear cells in relation to age and to sport activity

Variation in glucocorticoid sensitivity and the relation with obesity

Increasing evidence points to a relation between increased glucocorticoid (GC) exposure and weight gain. In support, long-term cortisol measurements using hair analysis revealed that many individuals with obesity appear to have cortisol values in the high physiological range. The mechanisms behind this relationship need to be determined in order to develop targeted therapy to reach sustainable weight loss in these subgroups. The effect of GCs is not only determined by the plasma concentration of GCs but also by individual differences in GC sensitivity and the target tissue, which can be analyzed by functional GC assays. GC sensitivity is influenced by multiple genetic and acquired (e.g., disease-related) factors, including intracellular GC availability, hormone binding affinity, and expression levels of the GC receptors and their isoforms, as well as factors involved in the modulation of gene transcription. Interindividual differences in GC sensitivity also play a role in the response to exogenous GCs, with respect to both therapeutic and adverse effects. Accordingly, in this review, we summarize current knowledge on mechanisms that influence GC sensitivity and their relationships with obesity and discuss personalized treatment options targeting the GC receptor.

The ratio of morning cortisol to CRP prospectively predicts first-onset depression in at-risk adolescents

RATIONALE

Early-onset adolescent depression is related to poor prognosis and a range of psychiatric and medical comorbidities later in life, making the identification of a priori risk factors for depression highly important. Increasingly, dysregulated levels of immune and neuroendocrine markers, such as C-reactive protein (CRP) and cortisol, have been demonstrated as both precursors to and consequences of depression. However, longitudinal research with adolescent populations is limited and demonstrates mixed immuno-endocrine-depression links.

OBJECTIVE

This study explored the putative bidirectional relationship between salivary measures of cortisol (Cort) and CRP, including the novel Cort:CRP ratio and depression.

METHODS

Participants from the randomized control trial 'Sleep and Education: learning New Skills Early' (SENSE) Study were 122 adolescents at risk for depression (73 females) aged 12-16 years (M = 12.71 years, SD = 1.01 years) assessed at baseline (T1), post-intervention (T2), and a two-year follow-up (T3).

RESULTS

Logistic regression results demonstrated that adolescents with higher T1 Cort:CRP_morn ratio levels were two-fold more likely to develop a first-onset depressive disorder from T2 to T3 as compared to adolescents with lower Cort:CRP_morn ratio levels, β = 0.73, t (36) = 2.15, p = .04, OR = 2.08. This effect was not moderated by treatment condition (β = -1.38, t (13) = -1.33, p = .20) and did not change when controlling for known risk factors for depression, including sex, age, body-mass index, socio-economic status, T1 anxiety disorder, nor T1 sleep disturbance, anxiety, or depressive symptoms (β = 0.91, t (31) = 2.14, p = .04).

CONCLUSION

Results highlight potential immuno-endocrine dysregulation as an underlying risk factor for adolescent first-onset depression, and may inform the development of targeted, preventative biobehavioral treatment strategies for youth depression.

Cellular senescence in the lung across the age spectrum

Cellular senescence results in cell cycle arrest with secretion of cytokines, chemokines, growth factors, and remodeling proteins (senescence-associated secretory phenotype; SASP) that have autocrine and paracrine effects on the tissue microenvironment. SASP can promote remodeling, inflammation, infectious susceptibility, angiogenesis, and proliferation, while hindering tissue repair and regeneration. While the role of senescence and the contributions of senescent cells are increasingly recognized in the context of aging and a variety of disease states, relatively less is known regarding the portfolio and influences of senescent cells in normal lung growth and aging per se or in the induction or progression of lung diseases across the age spectrum such as bronchopulmonary dysplasia, asthma, chronic obstructive pulmonary disease, or pulmonary fibrosis. In this review, we introduce concepts of cellular senescence, the mechanisms involved in the induction of senescence, and the SASP portfolio that are relevant to lung cells, presenting the potential contribution of senescent cells and SASP to inflammation, hypercontractility, and remodeling/fibrosis: aspects critical to a range of lung diseases. The potential to blunt lung disease by targeting senescent cells using a novel class of drugs (senolytics) is discussed. Potential areas for future research on cellular senescence in the lung are identified.

Aerobic Exercise Training and Inducible Inflammation: Results of a Randomized Controlled Trial in Healthy, Young Adults

Background Consensus panels regularly recommend aerobic exercise for its health-promoting properties, due in part to presumed anti-inflammatory effects, but many studies show no such effect, possibly related to study differences in participants, interventions, inflammatory markers, and statistical approaches. This variability makes an unequivocal determination of the anti-inflammatory effects of aerobic training elusive. Methods and Results We conducted a randomized controlled trial of 12 weeks of aerobic exercise training or a wait list control condition followed by 4 weeks of sedentary deconditioning on lipopolysaccharide (0, 0.1, and 1.0 ng/mL)-inducible tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and on toll-like receptor 4 in 119 healthy, sedentary young adults. Aerobic capacity by cardiopulmonary exercise testing was measured at study entry (T1) and after training (T2) and deconditioning (T3). Despite a 15% increase in maximal oxygen consumption, there were no changes in inflammatory markers. Additional analyses revealed a differential longitudinal aerobic exercise training effect by lipopolysaccharide level in inducible TNF -α ( P=0.08) and IL-6 ( P=0.011), showing T1 to T2 increases rather than decreases in inducible (lipopolysaccharide 0.1, 1.0 versus 0.0 ng/mL) TNF- α (51% increase, P=0.041) and IL-6 (42% increase, P=0.11), and significant T2 to T3 decreases in inducible TNF- α (54% decrease, P=0.007) and IL-6 (55% decrease, P<0.001). There were no significant changes in either group at the 0.0 ng/mL lipopolysaccharide level for TNF- α or IL-6. Conclusions The failure to support the primary hypotheses and the unexpected post hoc findings of an exercise-training-induced proinflammatory response raise questions about whether and under what conditions exercise training has anti-inflammatory effects. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 01335737.

Endocrine Effects of Relative Energy Deficiency in Sport

The term Relative Energy Deficiency in Sport was introduced by the International Olympic Committee in 2014. It refers to the potential health and performance consequences of inadequate energy for sport, emphasizing that there are consequences of low energy availability (EA; typically defined as <30 kcal·kg^-1 fat-free mass·day^-1) beyond the important and well-established female athlete triad, and that low EA affects populations other than women. As the prevalence and consequences of Relative Energy Deficiency in Sport become more apparent, it is important to understand the current knowledge of the hormonal changes that occur with decreased EA. This paper highlights endocrine changes that have been observed in female and male athletes with low EA. Where studies are not available in athletes, results of studies in low EA states, such as anorexia nervosa, are included. Dietary intake/appetite-regulating hormones, insulin and other glucose-regulating hormones, growth hormone and insulin-like growth factor 1, thyroid hormones, cortisol, and gonadal hormones are all discussed. The effects of low EA on body composition, metabolic rate, and bone in female and male athletes are presented, and we identify future directions to address knowledge gaps specific to athletes.

Actions and interactions of estradiol and glucocorticoids in cognition and the brain: Implications for aging women

Menopause involves dramatic declines in estradiol production and levels. Importantly, estradiol and the class of stress hormones known as glucocorticoids exert countervailing effects throughout the body, with estradiol exerting positive effects on the brain and cognition, glucocorticoids exerting negative effects on the brain and cognition, and estradiol able to mitigate negative effects of glucocorticoids. Although the effects of these hormones in isolation have been extensively studied, the effects of estradiol on the stress response and the neuroprotection offered against glucocorticoid exposure in humans are less well known. Here we review evidence suggesting that estradiol-related protection against glucocorticoids mitigates stress-induced interference with cognitive processes. Animal and human research indicates that estradiol-related mitigation of glucocorticoid damage and interference is one benefit of estradiol supplementation during peri-menopause or soon after menopause. The evidence for estradiol-related protection against glucocorticoids suggests that maintaining estradiol levels in post-menopausal women could protect them from stress-induced declines in neural and cognitive integrity.

Impact of glucocorticoid receptor density on ligand-independent dimerization, cooperative ligand-binding and basal priming of transactivation: a cell culture model

Glucocorticoid receptor (GR) levels vary between tissues and individuals and are altered by physiological and pharmacological effectors. However, the effects and implications of differences in GR concentration have not been fully elucidated. Using three statistically different GR concentrations in transiently transfected COS-1 cells, we demonstrate, using co-immunoprecipitation (CoIP) and fluorescent resonance energy transfer (FRET), that high levels of wild type GR (wtGR), but not of dimerization deficient GR (GRdim), display ligand-independent dimerization. Whole-cell saturation ligand-binding experiments furthermore establish that positive cooperative ligand-binding, with a concomitant increased ligand-binding affinity, is facilitated by ligand-independent dimerization at high concentrations of wtGR, but not GRdim. The down-stream consequences of ligand-independent dimerization at high concentrations of wtGR, but not GRdim, are shown to include basal priming of the system as witnessed by ligand-independent transactivation of both a GRE-containing promoter-reporter and the endogenous glucocorticoid (GC)-responsive gene, GILZ, as well as ligand-independent loading of GR onto the GILZ promoter. Pursuant to the basal priming of the system, addition of ligand results in a significantly greater modulation of transactivation potency than would be expected solely from the increase in ligand-binding affinity. Thus ligand-independent dimerization of the GR at high concentrations primes the system, through ligand-independent DNA loading and transactivation, which together with positive cooperative ligand-binding increases the potency of GR agonists and shifts the bio-character of partial GR agonists. Clearly GR-levels are a major factor in determining the sensitivity to GCs and a critical factor regulating transcriptional programs.

Glucocorticoid receptor mRNA expression in peripheral blood mononuclear cells in high trained compared to low trained athletes and untrained subjects

BACKGROUND

Physiological needs during prolonged exercise are a potent stimulus for the hypothalamic-pituitary-adrenal (HPA) axis. Hence, athletes undergoing daily endurance training sessions may have frequent and prolonged phases of endogenous hypercortisolism. Since chronic glucocorticoids treatment leads to down-regulation of glucocorticoid receptor alpha (GR-alpha) mRNA expression, endurance training could lead to modulation of GR expression.

AIM

The aim of the study was to evaluate GR-alpha and GR-beta mRNA expressions in peripheral blood mononuclear cells and plasma cortisol, ACTH and cortisol binding globulin (CBG) concentrations at rest in subjects undergoing different training regimes.

SUBJECTS AND METHODS

Nine high trained (HT) swimmers (training volume: 21.6+/-1.7 hours/week in 10-12 sessions) were compared with two age-matched control groups represented by 8 low trained (LT) runners (training volume: 6.4+/-2.6 h/week in 3-5 sessions) and 9 untrained subjects. Expression of GR was determined by RT-PCR of total RNA. Hormone levels were determined by radioimmunoassay methods.

RESULTS

HT athletes showed 10 times less GR-alpha mRNA expression than the untrained subjects, while LT athletes exhibited values about twofold less than the untrained subjects. GR-beta mRNA expression was undetectable in all subjects. No differences were observed among the three groups in hormone levels.

CONCLUSIONS

GR- alpha mRNA expression is repressed in proportion to the amount and frequency of the stressful stimuli due to training. Hence, this down-regulation may be a consequence of the frequent and prolonged exposure to cortisol acute elevations induced by training. GR-beta did not play an important role in inducing the down-regulation of GR-alpha mRNA expression observed.

Correlation between glucocorticoid receptor binding parameters, blood pressure, and body mass index in a healthy human population

Correlation between the glucocorticoid receptor (GR) number and affinity for the ligand, as well as the relationship between these equilibrium binding parameters and body mass index, blood pressure, and age were examined in peripheral blood mononuclear cells (PBMC) of healthy human subjects. It was found that the only statistically significant correlation was that between the GR number per cell and equilibrium dissociation constant, K(d) (r = 0.84, p < 0.0001). This observation implies the existence of a compensatory mechanism providing for lower GR affinity in individuals that have more receptor sites in circulating mononuclear cells and vice versa. This compensatory phenomenon together with considerable interindividual variation (GR number per cell ranging from 1391 to 15133, CV = 58.62%; and K(d) from 2.5 to 98.6 nM, CV = 80.87%), reflects plasticity of the glucocorticoid system. The results pose the question of whether this compensatory mechanism observed in healthy human subjects persists in pathophysiological states associated with glucocorticoid hormone actions and suggest that tissue sensitivity to glucocorticoids could be better predicted by the sign and magnitude of the correlation between the two receptor equilibrium binding parameters than by each of them separately.

Illuminating the interrelated immune and endocrine adaptations after multiple exposures to short immobilization stress by in vivo blocking of IL-6

Intermittent psychological stress was induced in adult rats by 2 h/day of immobilization stress for 4 days, with or without blocking the function of IL-6 by using an anti-IL-6 antibody. Basal concentrations of serum corticosterone, IL-1β, IL-6, and TNF-α were assessed 24 h after the last intervention, as were levels of glucocorticoid receptors (GR) and activities of glucocorticoid-inducible enzymes (tyrosine aminotransferase and glutamine synthetase) in muscle and liver. Whole blood cultures were used to assess both spontaneous and LPS-induced reactivity of peripheral blood mononuclear cells. Stress increased corticosterone concentration in a manner partially modulated by IL-6. Serum IL-1β concentration was downregulated during stress when IL-6 was blocked ( P < 0.01). LPS-induced IL-6 secretion by peripheral blood mononuclear cells in vitro correlated positively with serum IL-1β concentration in antibody-treated groups, independently of stress ( R = 0.70 in nonstressed and R = 0.78 in stressed rats; both P < 0.05), whereas serum corticosterone concentration correlated positively with LPS-induced secretion of IL-6 only in control rats ( R = 0.66; P < 0.05). Reductions in liver GR levels indicated independent effects of stress (34.5%) and anti-IL-6 antibody (16.7%) and additive effects for both (62.5%). Similar results are reported for vastus muscle. Conversely, stress increased tyrosine aminotransferase and glutamine synthetase activities in muscle and liver with a significant ( P < 0.05) effect of anti-IL-6 antibody only seen in stressed livers. In conclusion, IL-6 plays a role in maintaining circulating IL-1β concentration after multiple exposures to stress, thus promoting a continued elevation of corticosterone release; in peripheral tissues, IL-6 antagonizes the effects of glucocorticoids, especially at the level of GR concentration.

The unexpected anabolic phenotype and extended longevity of skin fibroblasts after chronic glucocorticoid excess

Intense stress can challenge tissue homeostasis and accelerate the ageing process. However, several lines of evidence indicate that repeated mild stresses can have beneficial and even life-prolonging effects. Hypersecretion of glucocorticoids (GC) represents the major hormonal response to stress. Besides its life-sustaining role, GC excess, usually due to several side-effects that promote a "catabolic" phenotype, can be detrimental for several tissues. Cushing's syndrome patients are characterized by chronic endogenous GC excess and consequently at the time of diagnosis they have an atrophic elderly-like skin. Interestingly, when Cushing's syndrome fibroblasts were removed from the high-GC milieu in vivo and cultured in vitro under standard conditions they express an "anabolic" phenotype, i.e. they restore their ability for collagen synthesis, they secrete reduced levels of metalloproteases (MMP-1 and MMP-2) and have an increased proliferative capacity and contractility. Furthermore, these cells exhibit a significant extension of their proliferative lifespan, while they respond better to exogenous stress by producing significantly higher levels of heat-shock protein-70 (HSP70). These results imply that long-term hypercortisolism in vivo can have beneficial consequences on fibroblast physiology in vitro.

Glucocorticosteroids in football: use and misuse

BACKGROUND AND OBJECTIVES

Glucocorticosteroids are widely used in medicine and have shown unchallenged therapeutic potential in several chronic inflammatory and other diseases. They are also widely used in sports medicine for the treatment of conditions such as asthma and acute injuries. In fact, as banned substances, most requests for therapeutic use exemption concern glucocorticosteroids. Nevertheless, their beneficial effect in certain conditions in sports, where inflammation is only a secondary reaction, remains to be validated. This paper aimed to provide a comprehensive review of the literature covering the therapeutic use of glucocorticosteroids since 1977 in conditions ranging from chronic rheumatic illness to peritendinous or intra-articular injection in acute injuries.

METHODS

Search of the medical literature published between 1977 and 2006 using PubMed. Articles relevant to the question "When and if at all is the use of glucocorticosteroids justified in football?" were selected and analysed.

RESULTS AND CONCLUSIONS

The findings clearly point out that, despite the common use of glucocorticosteroids in acute injuries in sports, there is actually limited evidence of the true benefits of such a practice. Physicians must take the possible adverse effects into consideration. In an athlete with clinically verified asthma, inhalational glucocorticosteroids remain first line therapy. Finally, for the purposes of education and prevention of misuse, it should be stressed that a measurable performance enhancing effect of glucocorticoids could not be proved on the basis of the results of the scientific studies to date.

Are the relationships between early activation of lymphocytes and cortisol or testosterone influenced by intensified cycling training in men?

The effects of exercise training on lymphocyte responses, as well as changes in circulating endocrine parameters at rest, were investigated. Seven male cyclists participated in a 4 week high-intensity (HI) cycling training intervention. Training improved performance significantly (peak power output (PPO): 1.4%, p < 0.05; 5 km time trial: 3.8%, p < 0.01; 40 km time trial: 0.4%, p < 0.05). Resting hormone concentrations (testosterone, sex hormone binding globulin (SHBG), cortisol, corticosteroid-binding globulin (CBG), and dehydroepiandrosterone-sulphate (DHEA-S)) were unchanged, with the exception of a 20% decrease in testosterone post-HI training (p < 0.067). Subjects' CD3+ cell counts decreased by 15% (p < 0.05), owing to significantly decreased CD4+ cell counts and slightly lower CD8+ and natural killer (NK) cell counts. Spontaneous in vitro CD69 expression increased in CD4+ cells (mean ± SD, pre: 12 ± 6 cells·µL-1; post: 35 ± 37 cells·µL-1; p < 0.05), but not in CD8+ cells (pre: 20 ± 29 cells·µL-1; post: 33 ± 16 cells·µL-1). Mitogen-induced CD69 expression decreased in both CD4+ (pre: 1570 ± 1258 cells·µL-1; post: 596 ± 597 cells·µL-1; p < 0.05) and CD8+ lymphocytes (pre: 676 ± 434 cells·µL-1; post: 412 ± 235 cells·µL-1; p < 0.05). Testosterone correlated positively with several immune parameters at baseline, whereas cortisol correlated negatively with parameters of the innate immune system post-HI training. We conclude that the stress of unaccustomed exercise is evident in resting lymphocytes, but not in resting endocrine parameters. However, correlations between testosterone and cortisol and immune parameters suggest that these 2 hormones play a role in modulating immune status. Our results indicate the importance of assessing both spontaneous and mitogen-induced aspects of immune-cell activation.Key words: CD69, DHEA, lymphocytes, exercise.

Healthy aging is associated with unaltered production of immunoreactive growth hormone but impaired neuroimmunomodulation

BACKGROUND

Both endocrine and immune systems are continuously remodeled during aging.

OBJECTIVE

Here, we investigated to what extent adrenal and somatosenescence are associated reciprocal changes in the immune system during strictly healthy aging.

METHODS

Forty-six elderly subjects and 33 young adults were recruited according to the health criteria of the SENIEUR protocol. Peripheral blood mononuclear cells were isolated and stimulated in vitro with lipopolysaccharide or phytohemagglutinin to assess the production of immunoreactive growth hormone (GH). Peripheral sensitivity to steroids was assessed in vitro by dexamethasone-, cortisol- or dehydroepiandrosterone (DHEA)-induced inhibition of T-cell proliferation. DHEA and GH levels were measured by radioimmunoassays.

RESULTS

Healthy elderly had lower salivary DHEA and serum GH levels (somatosenescence). They presented reduced T-cell sensitivity to dexamethasone but similar cellular sensitivities to cortisol and DHEA. Their cells produced similar levels of immunoreactive GH compared to the cells of young adults.

CONCLUSIONS

These data indicate that healthy aging is associated with adrenal and somatosenescence as well as impaired neuroendocrine immunoregulation at the level of the lymphocyte. In addition, somatosenescence may not be associated with a reciprocal decline in immunoreactive GH.

Avascular Necrosis of Femoral and/or Humeral Heads in Multiple Myeloma: Results of a Prospective Study of Patients Treated With Dexamethasone-Based Regimens and High-Dose Chemotherapy

Purpose

To assess the prevalence, time of onset, risk factors, and outcome of avascular necrosis (AVN) of bone in patients with multiple myeloma undergoing antineoplastic therapy.

Patients and Methods

A total of 553 consecutive assessable patients were enrolled onto a treatment protocol consisting of dexamethasone-containing induction chemotherapy, autologous stem-cell transplantation, consolidation chemotherapy, and maintenance with interferon alfa. Patients were randomly assigned to receive thalidomide (269 patients) or no thalidomide (284 patients) throughout the study period.

Results

With a median follow-up of 33 months (range, 5 to 114 months), AVN of the femoral head(s) developed in 49 patients (9%). Median time to onset of AVN was 12 months (range, 2 to 41 months). Three risk factors for AVN were identified by multivariate analysis: cumulative dexamethasone dose (odds ratio [OR], 1.028; 95% CI, 1.012 to 1.044; P = .0006 [per 40 mg dexamethasone]), male sex (OR, 0.390; 95% CI, 0.192 to 0.790; P = .009), and younger age (OR, 0.961; 95% CI, 0.934 to 0.991 per year; P = .0122). Thalidomide-treated patients had a prevalence of AVN similar to that of the control group (8% v 10%, respectively; P = .58). AVN-related pain and limited range of motion of the affected joint were present in only nine and four patients, respectively, and four patients underwent hip replacement because of AVN. Fluorine-18 fluorodeoxyglucose positron emission tomography failed to detect abnormal uptake in the AVN-affected bones.

Conclusion

AVN is a rare and usually asymptomatic complication during myeloma therapy. Cumulative dexamethasone dose, male sex, and younger age, but not thalidomide, increase the risk of AVN.

Overnight Urinary Cortisol and Cortisone Add New Insights into Adaptation to Training

PURPOSE

To examine the effects of training on the HPA axis using two new noninvasive tools: salivary cortisol response to awakening and overnight urinary cortisol and cortisone excretion, and on the sympathoadrenal system using overnight catecholamines excretion. To dissociate the effects of training to those of seasonal hormonal variations, endurance-trained men were compared with sedentary men.

METHODS

Nine untrained (UT) men and 10 triathletes were followed during a 10-month season. Clinical (total score of fatigue, total training load, and performances during the competition period) and hormonal parameters (overnight excretion of glucocorticoids and catecholamines, increment of saliva cortisol response to awakening) were measured.

RESULTS

Significant seasonal variations in overnight urinary glucocorticoids (decreased in June) and catecholamines (increased in June) concentrations and in saliva cortisol response to awakening were depicted in the two groups. Whereas urinary cortisol excretion was similar between both groups, overnight urinary cortisone excretion was significantly higher in triathletes compared with UT men (ANOVA: training effect: F(2,45) = 9.50, P = 0.0003), suggesting that during a resting day there is a higher inactivation of cortisol into cortisone in highly trained men. Two triathletes developed an overtraining syndrome and presented an increased urinary cortisol/cortisone ratio (>1) due to lower cortisone inactivation compared with the triathlete group.

CONCLUSION

: When not taken into account, seasonal variations may induce errors in the interpretation of hormonal variations with training. The increased intracellular inactivation of cortisol during the night in endurance-trained men uncovers subtle changes in HPA function during training. We show in this study the interest of noninvasive biological markers of the activity of the neuroendocrine system to monitor the repercussion of training load during longitudinal follow-up of athletes.

Stress, glucocorticoids and ageing of the immune system

Ageing has been associated with immunological changes (immunosenescence) that resemble those observed following chronic stress or glucocorticoid (GC) treatment. These changes include thymic involution, lower number of naïve T cells, reduced cell-mediated immunity, and poor vaccination response to new antigens. It follows that immunosenescence could be associated with changes of peripheral GC levels. Indeed, when compared with young subjects, healthy elders are more stressed and show activation of the hypothalamus-pituitary-adrenal (HPA) axis. However, both beneficial and undesirable effects of GCs ultimately depend on the target tissue sensitivity to these steroids. Recent data indicate that peripheral lymphocytes from elders respond poorly to GC treatment in vitro. The present review summarizes recent findings which suggest that immunosenescence may be closely related to both psychological distress and stress hormones. Furthermore, chronically stressed elderly subjects may be particularly at risk of stress-related pathology because of further alterations in GC-immune signalling. Finally, the neuroendocrine hypothesis of immunosenescence is finally reconsidered in which the age-related increase in the cortisol/DHEA ratio is major determinant of immunological changes observed during ageing.

Basal and glucocorticoid induced changes of hepatic glucocorticoid receptor during aging: relation to activities of tyrosine aminotransferase and tryptophan oxygenase

The characteristics of glucocorticoid receptors, their sensitivity to glucocorticoid as well as the basal and glucocorticoid induced thyrosine aminotranferase (TAT) and tryptophan oxygenase (TO) activities were studied in rat liver during aging. The concentration (N) and dissociation constant (K(d)) of glucocorticoid receptor (GR) significantly change during the aging both in untreated and dexamethasone treated animals. The level of receptors was lower in dexamethasone treated rats of all analyzed aged groups compared to untreated animals. In comparison to untreated groups, there was no correlation between the changes of N and K(d) during the lifespan. According to immunochemical analysis, the decline of receptor protein content occurs during lifespan. Dexamethasone treatment reduced the level of receptor protein compare to respective age group of untreated rats. The glucocorticoid-receptor (G-R) complexes from both untreated and treated animals underwent thermal activation, although the extent of activation was more pronounced in the case of untreated groups compared to treated animals. The magnitude of heat activation of receptor complexes was more pronounced in the liver of the youngest untreated rats compared to elderly ones, while the receptor activation between treated groups of studied ages has shown less significant differences. Besides, basal as well as induced TAT and TO activities after dexamethasone injection also showed age-related alterations. The observed alterations in GR might play a role in the changes of the cell responses to glucocorticoid during the age. This presumption is supported by detected changes in basal and dexamethasone induced TAT and TO activities during aging.

Effects of chronic and acute training on glucocorticoid receptors concentrations in rats

The effects of chronic endurance training and acute exercise on glucocorticoid receptors were investigated in rats. For chronic endurance training, rats were exposed to progressive running training on a motor-driven treadmill for 3, 5 and 7 weeks, twice a day and 6 days a week. The samples were taken, 34-36 hours after the last exercise bout. Some of the 7-week training rats were killed by decapitation 7 days following the last exercise bout. The glucocorticoid receptors in hepatic cytosol in 5-week and 7-week rats decreased as compared to the sedentary control. There was no significant difference between the glucocorticoid receptors in hepatic cytosol in some of the 7-week rats those who had stopped training for 7 days and those in the controls. The chronic endurance training did not lead to change of the apparent dissociation constant (Kd). The changes of glucocorticoid receptors after acute exercise have also been investigated and it showed profound decreases of glucocorticoid receptors in renal and myocardial cytosol in low intensity (swimming without an extra weight for 60 minutes) and high intensity (swimming with a weight equal to 6% of body mass for 60 minutes) training groups. The decreases in glucocorticoid receptors in renal and myocardial cytosol were less prominent after low intensity training. These results demonstrated that both acute exercise training and chronic endurance training could lead to a decrease in glucocorticoid receptors, which was in a training intensity- and training load volume-dependent manner, and the changes in glucocorticoid receptors during exercise training were reversible.

Relationship between dexamethasone-inhibited lysozyme activity in peripheral mononuclear leukocytes and the cortisol and glucocorticoid receptor response to dexamethasone

The assessment of lysozyme activity in mononuclear leukocytes (MNLs) following the in vitro administration of dexamethasone (DEX) provides a measure of peripheral glucocorticoid sensitivity. The goal of the present study was to determine the relationship between the IC(50) of lysozyme activity following such challenge, and the cortisol response to oral administration of 0.50 mg DEX in 18 healthy subjects. The results demonstrated a robust association between the IC(50) and both cortisol decline and percent suppression of cortisol in response to low-dose DEX. However, this measure was uncorrelated with pre or post DEX cortisol levels or GR number. The high correlation between the inhibitory effect of DEX on lysozyme synthesis and two measures reflecting cortisol suppression in response to oral DEX reflects the similarities of GC responsiveness in both in vivo and in vitro models, and suggests that the in vitro assessment of lysozyme activity in MNLs may be useful in the study of neuropsychiatric or other clinical disorder.

Heavy load exercise induced dysfunction of immunity and neuroendocrine responses in rats

To determine whether immunity and neuroendocrine system is altered by different loads of exercise training in rats, eight-week-old male Sprague-Dawley rats were randomly assigned to one of the three groups: 1) cage control group (CCG); 2) moderate load training (MLT) (swimming at the intensity of 1.4 m/sec water flowing for 60 min per day); 3) heavy load training (HLT) (swimming at the intensity of 1.8 m/sec water flowing for 120 min per day). MLT and HLT rats were assigned to swim for 6 days per week for total of 6 weeks. All rats were sacrificed 36 h after their last training session. Splenocytes were pooled for assay of cell proliferation and neuropeptide contents in the hypothalamus, hypophysis and plasma were determined by radioimmunoassay while glucocorticoid specific binding in intact thymus was measured by radioligand binding assay. All rats were weighed weekly. The results showed that after 6-week training, rat splenocyte proliferation in response to Con A and LPS decreased in HLT rats compared with MLT and CCG rats. In addition, the contents of beta-endorphin, dynorphin A, arginine vasopressin and oxytocin in the hypothalamus, hypophysis and plasma were altered by HLT, as shown by increased plasma concentration of glucocorticoids and decreased glucocorticoids specific binding in intact thymus compared with MLT and CCG. Furthermore, a decreased body mass in HLT rats has been observed. The body mass of HLT rats was significantly lower than that in CCG and MLT rats at the end of the swimming training period. These data suggest that 6-week heavy load training induces the dysfunction of immunity and neuroendocrine responses, which might be one of the underlying mechanisms of immune dysfunction in overtraining.

Dependence of rat hippocampal c-Fos expression on intensity and duration of exercise

The expression of c-Fos, an immediately early gene, is a marker of neural activity. In the present study, the effect of treadmill exercise on c-Fos expression was investigated in various regions of the rat hippocampus via immunohistochemistry. The first part of the experiment was aimed at determining the dependence of c-Fos expression on the intensity of treadmill exercise. In most of the hippocampal regions studied, increasing c-Fos expression was observed with increasing exercise intensity. In the second part of the experiment, the dependence of c-Fos expression on the duration of treadmill exercise was investigated. The c-Fos expression induced by mild-intensity exercise increased until the 7th day of exercise and subsequently decreased. Results of the present study suggest that the effect of treadmill exercise on neuronal activity in the hippocampus is intensity-and duration-dependent.

Pregnancy is associated with suppression of the nuclear factor kappaB/IkappaB activation pathway in peripheral blood mononuclear cells

Modulations of maternal immune cell function are critical for successful growth and development of an antigenically distinct fetus. It has been proposed that pregnancy is associated both with suppression of the adaptive immune system and a generalised maternal inflammatory response with changes in immune function resembling those associated with septicemia, and these changes are more exaggerated when pregnancies are complicated with pre-eclampsia. The nuclear factor (NF)-kappaB family of transcription factors play a significant role in immune regulation. We hypothesised therefore that if pregnancy is associated with activation of the maternal immune system, this would be supported by the activation of NF-kappaB and degradation of IkappaBalpha and beta in peripheral blood mononuclear cells (PBMCs). We demonstrate the contrary: NF-kappaB activity is suppressed in PBMCs from pregnant females and more in pre-eclampsia. The inhibition of NF-kappaB activation in pregnancy is not attributed to over-expression of IkappaBalpha or beta. In contrast, levels of IkappaBalpha and beta in cytoplasmic extracts from PBMCs in pregnancy are decreased compared with non-pregnant controls, and IkappaBalpha levels are decreased more so in pre-eclampsia. We have shown that activation of NF-kappaB in PBMCs from patients with septicemia follows the classical pathway. This pathway is differentially regulated in pregnancy. Alterations in NF-kappaB nuclear binding and IkappaBalpha levels were reproducible by culturing PBMCs in pooled pregnant serum. Taken together, these data indicate that pregnancy-specific factors exist to regulate expression of NF-kappaB/IkappaB in a pregnancy-specific manner, and may underlie one mechanism by which the fetus avoids maternal rejection throughout pregnancy.

Effects of oestrogen and exercise on caspase-3 activity in primary and secondary lymphoid compartments in ovariectomized mice

This study investigated the effect of oestrogen exposure and exercise on caspase-3 activity, a measure of apoptosis, in lymphocytes from the thymus, spleen, and lymph nodes in ovariectomized mice. Fifty-nine female B6D2F1 mice were randomized to hormone and exercise conditions. Hormone treatment consisted of implantation with oestradiol pellets (0.72 mg oestradiol) or placebo pellets (0 mg) for 21 days following bilateral ovariectomy (OVX). Exercise consisted of a single treadmill exercise bout (26 m min(-1), 6 degrees slope, 90-min) or sedentary condition. Mice were killed and the thymus, spleen and lymph nodes were removed for the determination of caspase-3 expression by enzyme-linked immunosorbent assay (ELISA), serum oestrogen levels by RIA, and tissue weights. Body weights were monitored throughout the study. In the thymus, oestrogen exposure, exercise and both treatments together were associated with higher caspase-3 activity (P < 0.05) and lower thymus weights (P < 0.05). In contrast, oestrogen exposure and exercise treatment were not associated with greater caspase-3 activity or change in tissue weight in secondary lymphoid tissues (spleen, lymph nodes). Oestrogen-replaced OVX mice had a higher concentration of plasma oestradiol than placebo OVX mice (P < 0.05).

CONCLUSION

The results suggest that oestrogen and treadmill exercise are associated with greater apoptosis, as measured by caspase-3 activity, in the thymus but not in the spleen or lymph nodes. Clinical studies will be necessary to determine if women who take oestrogen have higher rates of apoptosis in primary lymphoid tissues and the significance of thymocyte apoptosis for maintenance of cellular immune function during the post-menopausal years.

Inhibitory effects of voluntary wheel exercise on apoptosis in splenic lymphocyte subsets of C57BL/6 mice

Two-month-old mice were placed in cages with (Ex) or without exercise running wheels with free access to the wheel 24 h/day for 10 mo. An equal amount of food for both groups was provided daily. Ex mice ran an average of 33.67 km/wk initially, and exercise decreased gradually with age. Ex mice had gained an average of 43.5% less body weight at the end of the experiment. Although serum lipid peroxides were not altered by exercise, superoxide dismutase and glutathione peroxidase activities in serum were significantly increased. Flow cytometric analysis of spleen cells revealed an increased percentage of CD8+ T cells and a decreased percentage of CD19+ B cells in Ex mice (P < 0.05). Exercise decreased apoptosis in total splenocytes and CD4+ cells incubated with medium alone or with H(2)O(2), dexamethasone, tumor necrosis factor-alpha (TNF-alpha), or anti-CD3 monoclonal antibody (P < 0.05) and CD8+ cells with medium alone or with TNF-alpha (P < 0.05). Even though exercise did not alter the intracellular cytokines (TNF-alpha and interleukin-2) or Fas ligand, it did significantly lower interferon-gamma in CD4+ and CD8+ cells (P < 0.05). In summary, voluntary wheel exercise appears to decrease H(2)O(2)-induced apoptosis in immune cells as well as decrease interferon-gamma production.

Effect of maturation on the osteogenic response of cultured stromal bone marrow cells to basic fibroblast growth factor

Formation of bone-like tissue in culture by stromal bone marrow cells (SBMC) derived from young growing rats is dependent on dexamethasone (Dex) (Cell Tissue Res 254:317; 1988) and is significantly enhanced by basic fibroblast growth factor (bFGF) (J Bone Miner Res 8:919; 1993). The aim of this study was to examine the effect of maturation on the osteogenic potential and the response to Dex and bFGF of SBMC by using cultures derived from young growing (6 weeks old) and adult (9 months old) rats. SBMC cultures were grown in the presence of Dex (10(-8) or 10(-7) mol/L) at both P(0) and P(1) and either in the presence or absence of bFGF. The effect of Dex and bFGF on mineralized bone-like tissue (MBT) formation was assessed at P(1). The highest levels of mineralized tissue formation in P(1) subcultures in the absence of bFGF were obtained when cultures derived from young rats (6 weeks old) were treated with Dex 10(-7) and 10(-8) mol/L at P(0) and P(1), respectively, and when cultures derived from adult rats were exposed to Dex 10(-8) mol/L both at P(0) and P(1). Under these optimal Dex concentrations, the amount of MBT formed by adult rat-derived cultures was 15-fold lower than that of young rat-derived ones. The addition of bFGF to P(0) cultures or to P(1) cultures grown under optimal Dex conditions enhanced MBT formation in P(1) cultures derived from both young and adult rats, but this effect was considerably more pronounced in the adult rat-derived cultures. The maximal levels of MBT formation were produced by cultures derived from adult rats treated with bFGF at both P(0) and P(1), whereas in cultures derived from young rats, the addition of bFGF at P(0) was not necessary for maximal MBT production. This stimulating effect of bFGF on MBT formation by adult rat-derived cultures was accompanied by a 2.2-, 1.8-, and 4.3-fold increase in proliferation, alkaline phosphatase activity, and Ca(2+) deposition rate, respectively. bFGF increased the level of glucocorticoid receptor by approximately 2. 3-fold in Dex-treated cultures derived from young animals. These results indicate that maturation is associated with a decrease in the proportion of osteoprogenitor cells in the stromal bone marrow and in their capacity to express the osteogenic phenotype. They further point to the significant role of bFGF in stimulating proliferation and osteogenic expression of stromal bone marrow osteoprogenitors derived from adult rats.

Glucocorticoid receptors in anorexia nervosa and Cushing's disease

BACKGROUND

Patients with anorexia nervosa do not display cushingoid features in spite of elevated cortisol plasma levels. Whether a cortisol resistance or a reduced availability of the metabolic substrates necessary to develop the effect of glucocorticoids is responsible for this has not been established.

METHODS

Twenty-two patients with severe restrictive anorexia nervosa, 10 patients with active Cushing's disease, and 24 healthy volunteers without psychiatric disorders or mood alterations were investigated. Glucocorticoid receptor characteristics were examined on mononuclear leukocytes by measuring [3H]dexamethasone binding and the effect of dexamethasone on [3H]thymidine incorporation, which represents an index of DNA synthesis.

RESULTS

The number of glucocorticoid receptors on mononuclear leukocytes (MNL) was comparable in patients with anorexia nervosa, patients with active Cushing's disease, and normal subjects (binding capacity 3.3 +/- 0.23 vs. 3.7 +/- 0.30 and 3.5 +/- 0.20 fmol/10(6) cells). Conversely, glucocorticoid receptor affinity was significantly decreased in anorexia nervosa as well as in Cushing's patients compared to control subjects (dissociation constant 4.0 +/- 0.31 and 4.1 +/- 0.34 vs. 2.9 +/- 0.29 nmol/L, p < .001) and inversely correlated with the levels of urinary free cortisol in both groups of patients. Basal [3H]thymidine incorporation in MNL was significantly reduced in anorexia nervosa as well as in Cushing's patients compared to control subjects (p < .001) and was diminished by dexamethasone to an extent similar to control subjects in patients with anorexia nervosa, but significantly (p < .001) less in those with Cushing's disease. In patients with anorexia nervosa, the incorporation of [3H]thymidine into the MNL was inversely correlated with urinary free cortisol levels.

CONCLUSIONS

These data indicate that the lack of cushingoid features in patients with anorexia nervosa is not ascribable to a reduced sensitivity to glucocorticoids but is more likely due to the paucity of metabolic substrates.